1. Field of the Invention
The invention relates to an improved cross element for a transmission belt for a continuously variable speed regulator, in particular to be used in a transmission system, and to an improved method for the production thereof.
2. Description of the Prior Art
A cross element of the kind referred to is e.g. known from EP No. 0 014 492 and EPA No. 0 143 293. A transmission belt as referred to here has a substantially trapezoidal section for use on V-shaped pulleys and consists of an endless carrier in the shape of at least one metal band and of a number of cross elements butting against each other with the parallel parts of their main sides and provided displaceably on the carrier. With the transmission belts known up to now and the cross elements used therein satisfactory results were attained. A drawback of the existing transmission belts is that on passing over the pulleys the stability is not satisfactory at some speeds, which manifests itself in vibrations in directions perpendicular to the direction of movement in the linear part between the pulleys (see FIG. 26).
When the invention was being conceived it appeared that part of the problems could be traced back to an insufficient plan-parallelism of the cross elements in mounted condition. Besides that there is the problem that the production rate of cross elements made with great precision is experienced as being insufficient.
Up to now cross elements have been made by blanking them out of pre-profiled strip material. This is a relatively slow process. The inventors felt the need to replace this process by the so-called "Progressive Die" technique, which method can lead to high production rates. It became apparent to them, however, that the use of this technique is not suitable for the cross elements known so far, because the dimensional accuracy of the elements obtained is insufficient or can only be achieved with too great an effort.